【作者】 姜燕；

【导师】 王耀南；

【作者基本信息】 湖南大学 ， 电气工程， 2013， 博士

【摘要】 直驱型永磁同步风力发电被认为是最具优势和发展前景的发电方式之一。风力发电并网技术作为风能利用的最主要技术手段，更是成为各国研究者关注的焦点。全功率变流器是实现发电能量馈入电网的唯一部件，因此全功率变流器的控制性能和可靠性在系统中至关重要。风能并网技术要求的不断提高、风力发电系统容量的不断增大，对变流器控制技术提出了更高的要求。本文选择直驱型永磁同步风力发电系统全功率变流器作为研究对象，深入研究了无位置传感器控制、谐波抑制、环流控制及软件锁相等方面相关技术，具有重要的学术意义和工程价值。论文的主要工作如下：(1)分析了永磁同步发电机、PWM变流器以及直流母线环节的数学模型，介绍了直驱型永磁同步风力发电系统机侧变流器和网侧变流器的控制策略。提出了一种基于最优定界椭球的无位置传感器辨识算法，为控制策略提供精确的转子位置和速度信号，仿真分析表明，该算法在电机运行状态或系统参数改变时具有较好的辩识效果。在搭建的直驱型永磁同步风力发电系统模拟实验平台上，对基于双PWM变流器的控制策略进行了实验研究，实验结果表明了控制策略的正确性与可行性。(2)在两相静止坐标系下，分别对机侧和网侧PWM变流器进行了数学建模。为了解决传统PI控制算法无法对交流信号进行无差调节的问题，将比例谐振控制器（PR控制器）引入到直驱风电系统双PWM变流器的电流调节中。提出了一种基于PR控制器的谐波补偿方法，并分别从机侧和网侧两个方面进行了深入研究，搭建了仿真模型和模拟实验平台。仿真和实验结果表明，该方法能够较好地对系统中谐波电流进行补偿，从而达到提高电能质量的目的。补偿方法简单方便，有效减少了坐标变换次数，易于工程实现。(3)在建立并联变流器数学模型的基础上，分析了直接并联和交错并联变流器中的环流问题。通过引入零序电流闭环，提出了一种基于改进SVPWM控制方法，并设计了环流控制器。分别运用传统SVPWM和改进SVPWM两种不同的调制算法，对交错并联变流器的运行特性进行了仿真，搭建了模拟实验平台。仿真分析与实验结果表明，多台变流器并联运行时，系统各个模块之间存在较大的零序环流，但在交错并联运行方式下，变流器之间的一些高次电流谐波能相互抵消，电能质量由此得以提高。基于改进SVPWM控制方法不仅提高了电压利用率，而且有效地抑制了变流器并联运行产生的环流，削弱了环流低频振荡，同时实现了各并联变流器的独立运行。(4)研究了传统的单同步坐标系软件锁相法、基于对称分量法的单同步坐标系软件锁相法、改进的单同步坐标系软件锁相法、解耦的双同步坐标系软件锁相法等几种常见软件锁相方法的优缺点，并通过仿真，分析了这几种方法在电压、频率和相位变化时的锁相性能。针对电网电压不平衡与电网电压恶化情况下，上述几种锁相方法存在的锁相缺陷，提出了一种新型的软件锁相方法。该方法采用全通滤波器和简单数学运算，分离出d-q同步旋转坐标系下的正序分量，再提取相位以达到锁相目的。详细分析了新型锁相方法的工作原理，并通过仿真与实验验证了新型锁相环在不平衡输入电压与电网电压恶化情况下具有更优的性能。更多还原

【Abstract】 Direct-drive permanent magnet synchronous wind power generation has wideapplications and prospects for development. As one of the main technical methods towind power utilization, wind power network technology became the focus of allresearchers. Full-power converters are the unique part to feed the energy into powergrid, and their control performance and reliability play a crucial role in the system. Inorder to meet the improvement of interconnection technology and the increase ofconverter power level, the performance for control methods of full-power convertersare much higher. Full-power converter was selected as study object in this dissertation,and related technologies of sensorless control, harmonic compensation, circulationcurrent control and software phase-locked were researched deeply, which haveimportant academic significance and engineering value. The main works are asfollows：(1) The mathematical models of permanent magnet synchronous generator, PWMconverter and the DC bus were analyzed. The control strategies of machine-sideconverter and grid-side converter were described. A sensorless identification algrithmbased on optimal bounded ellipsoid was proposed, which can produce accurate ro torposition and speed signals. The simulation results show it has better identificationeffects when motor operation status and system parameter changed. On the simulatedplatform for dual-PWM direct-drive permanent magnet synchronous wind powergeneration system, experiments were done. And the results indicate the correctnessand feasibility of all kinds of control strategies.(2) Mathematical models for PWM converter of machine-side and grid-side wereconducted under two-phase static coordinate. Inorder to solve the problem thattraditional PI control algorithm cannot realize zero error adjustment of AC signal, PRcontroller was introduced to converter current regulation in direct-drive permanentmagnet synchronous wind power system. A harmonic compensation method based onPR controller was proposed. The compensation methods for machine-side andgrid-side were deeply discussed respectively. The model and simulated platform werebuilt, and the simulation and experiment results indicate that harmonic current can becompensated perfectly by using this method, thus the power quality can be enhanced.The harmonic compensation method is simple, convenient and can effectively reduce the number of coordinate transformations and alos it is easy to be engineeringimplemente.(3) Based on the establishment of mathematical model for converter underparallel topology, the analysis of circulation current in converter under direct andinterleaved parallel topology. A novel control method based on improved SVWPMmodulation algorithm was proposed by introducing the zero-sequence current closedloop, and the circulation current controller was designed. By using traditional andimproved SVPWM modulation algorithm respectively, the simulation of operationperformance for interleaved parallel converter was conducted, and the simulatedplatform was built. The simulation and experiment results demonstrate thatzero-sequence circulation current exists in parallel converters, but some higherharmonic can offset each other in interleaved parallel system, the power quality canbe enhanced. By using improved SVPWM algorithm, the voltage utilization ratio canbe raised, the circulation current can be suppressed effectively, and the oscillation oflow frequency circulation can be weakened. Meanwhile, the converters can operateindependently.(4) The advantages and disadvantages of several software phase-locked methodsbased on traditional single synchronous reference coordinate, symmetrical elementsingle synchronous reference coordinate, improved single synchronous coordinate anddecoupled double synchronous coordinate were studied. Their performance wassimulated at different voltage, frequency and phase. For the defects of softwarephase-locked methods mentioned above at unbalance and deterioration of grid voltage,a novel software phase-locked method was put forward. By using all-pass filter andsimple mathematic calculation, positive-sequence voltage component in asymmetricpower grid under d-q synchronous rotating reference coordinate was extracted, andthen the phase can be extracted to realize phase locking. Its working principle wasstudied in detail. The simulation and experiment results indicate that the novelphase-locked loop shows better performance in case of unbalance and dete rioration ofgrid voltage.更多还原